Educability-and-Group-Differences-1973-by-Arthur-Robert-Jensen

Equating for Socioeconomic Variables 237
studies which have attempted to control for SES by actual matching
or by statistical equating of groups. In reviewing all the studies of
this type up to 1965, Shuey (1966, p. 518) summarizes the results
as follows:
With two exceptions, the colored averaged below the white
groups in mental test performance in all of the 42 investigations.
[The two exceptions were studies which showed ambiguous
results or presented insufficient statistical analysis to permit an
evaluation.] Average IQs were reported in 33 of the studies
including a total of about 7,900 colored and 9,300 white Ss,
and from these a mean difference of 11 points favoring the
whites was obtained [in contrast to a mean difference of 15-16
IQ points when random samples are compared]. . . . Twentyfive
of the 41 studies were located in the North, and in at least
fourteen of the researches the colored and white children were
not only attending the same school, but were living in the same
district or neighborhood. The combined mean difference in
IQ between the 2,760 colored subjects tested in the North and
the whites of comparable socioeconomic status or occupation
was 7-6. Nearly all of these 5s in the eighteen studies were
of school age, the whites and Negroes attending the same
school and living in the same areas, many with large Negro
populations.
A more recent study by Tulkin (1968) controlled not only SES
but a number of subtle family environmental factors. Controlling
SES alone did not overcome the racial difference in mean IQ.
After the familial behavioral differences were equated, however,
Tulkin concluded, ‘When family differences were also statistically
controlled, there were no significant racial differences on test
scores in the upper socioeconomic group, although differences
remained significant in the lower socioeconomic group.’ Two
critical points should be made about this particular study, however.
First, the upper SES Negro group was small (N = 52), and though
it did not show a statistically significant difference from the white
upper SES group, the difference was in the same direction as in
most other studies.3 Second, Tulkin’s analysis, which controlled
(by covariance analysis) for various family factors within SES
groups, was based on a composite score of verbal and non-verbal
IQ plus five scholastic achievement tests. The composite score is